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Appeared on: Thursday, November 04, 2010
New Hologram Technology Brings 3D Telepresence To Life

A team led by the University of Arizona's Nasser Peyghambarian has
developed a new type of holographic telepresence that allows the
projection of a three-dimensional moving image without the need for
special eyewear such as 3D glasses or other auxiliary devices.

Remember the Star Wars scene in which R2D2 projects a three-dimensional
image of a troubled Princess Leia delivering a call for help to Luke
Skywalker and his allies? What used to be science fiction is now close to
becoming reality thanks to a breakthrough in 3D holographic imaging
technology developed at the University of Arizona College of Optical
Sciences.

The technology is likely to take applications ranging from telemedicine,
advertising, updatable 3D maps and entertainment to a new level.

The journal Nature chose the technology to feature on the cover of its
Nov. 4 issue.

"Holographic telepresence means we can record a three-dimensional image in
one location and show it in another location, in real-time, anywhere in
the world," said Peyghambarian, who led the research effort.

"Holographic stereography has been capable of providing excellent
resolution and depth reproduction on large-scale 3D static images," the
authors wrote, "but has been missing dynamic updating capability until
now."

The prototype device uses a 10-inch screen, but Peyghambarian's group is
already successfully testing a much larger version with a 17-inch screen.
The image is recorded using an array of regular cameras, each of which
views the object from a different perspective. The more cameras that are
used, the more refined the final holographic presentation will appear.

That information is then encoded onto a fast-pulsed laser beam, which
interferes with another beam that serves as a reference. The resulting
interference pattern is written into the photorefractive polymer, creating
and storing the image. Each laser pulse records an individual "hogel" in
the polymer. A hogel (short for holographic pixel) is the
three-dimensional version of a pixel, the basic units that make up the
picture.

The hologram fades away by natural dark decay after a couple of minutes or
seconds depending on experimental parameters. Or it can be erased by
recording a new 3D image, creating a new diffraction structure and
deleting the old pattern.

Peyghambarian explained: "Let's say I want to give a presentation in New
York. All I need is an array of cameras here in my Tucson office and a
fast Internet connection. At the other end, in New York, there would be
the 3D display using our laser system. Everything is fully automated and
controlled by computer. As the image signals are transmitted, the lasers
inscribe them into the screen and render them into a three-dimensional
projection of me speaking."

The overall recording setup is insensitive to vibration because of the
short pulse duration and therefore suited for industrial environment
applications without any special need for vibration, noise or temperature
control.

One of the system's major hallmarks never achieved before is what
Peyghambarian's group calls full parallax: "As you move your head left and
right or up and down, you see different perspectives. This makes for a
very life-like image. Humans are used to seeing things in 3D."

The work is a result of a collaboration between the UA and Nitto Denko
Technical, or NDT, a company in Oceanside, Calif. NDT provided the polymer
sample and media preparation. "We have made major advances in
photorefractive polymer film fabrication that allow for the very
interesting 3D images obtained in our upcoming Nature article," said
Michiharu Yamamoto, vice president at NDT and co-author of the paper.

Potential applications of holographic telepresence include advertising,
updatable 3D maps and entertainment. Telemedicine is another potential
application: "Surgeons at different locations around the world can observe
in 3D, in real time, and participate in the surgical procedure," the
authors wrote.

The system is a major advance over computer-generated holograms, which
place high demands on computing power and take too long to be generated to
be practical for any real-time applications.

Currently, the telepresence system can present in one color only, but
Peyghambarian and his team have already demonstrated multi-color 3D
display devices capable of writing images at a faster refresh rate,
approaching the smooth transitions of images on a TV screen. These devices
could be incorporated into a telepresence set-up in near future.